EP0449686B1 - Telescopic mobile equipment for driving a reciprocating pump - Google Patents

Abstract

The slide 8 of the moving element of the pump is in two telescopic sections 15 and 16, the one (15) coupled to the diaphragm, the other (16) coupled to the eccentric cam and connected together by a disengageable connecting device (19) when the flow regulating stop (28) obstructs the travel of the part (15). <IMAGE>

Description

There are two categories of diaphragm pumps: pumps in which the diaphragm is hydraulically actuated and those in which the diaphragm is mechanically actuated. In hydraulically actuated pumps, a reciprocating piston acts in a chamber which contains a determined volume of "motor" liquid, one of the walls of the chamber being formed by the membrane to be actuated. The depression of the piston in this control chamber pushes the membrane back into the working chamber which sees its volume decrease. This is the pump discharge phase. In its reverse stroke, the piston creates a suction of the control liquid which drives the membrane backwards. The volume of the working chamber increases. This is the suction phase of the pump. The suction height in this type of pump is limited by the cavitation of the working liquid.

In the case of a pump with a mechanically actuated diaphragm, this diaphragm is coupled to a mobile assembly driven by an alternating movement. There are several motor mechanisms for the moving assembly, of the crank-rod type or rather a slide coupled to an eccentric. For some of them, the eccentric acts like a cam which pushes the moving part (pump delivery phase), the return being ensured elastically. For others, the mobile assembly is coupled to the eccentric by means of a coupling nut which provides the return drive.

The adjustment of the flow rate of these diaphragm pumps consists of acting on two operating parameters: the amplitude of the stroke and the cadence. In practice, one acts on the rate by allowing an adjustment of the speed of the eccentric drive motor. Regarding the adjustment of the stroke amplitude, the mechanisms depend on the technology of the pumps. Thus for hydraulically controlled pumps, it is possible to adjust, for a constant amplitude of stroke of the piston, the quantity of displaced control liquid. To do this, the control chamber is in part contained by a cavity in the piston which has lateral orifices for communication with the reservoir, these orifices being discovered over an adjustable part of the stroke around the rear dead center of the piston (at the end of the suction phase). To illustrate this technique, document EP 148 691 will be cited.

Furthermore, for mechanically actuated pumps, the stroke adjustment is generally carried out by limiting the return amplitude of the slide under the effect of the return spring by means of an adjustable stop, as for example documents US-A- 4,167,896 or GB-A- 2,044,895.

There is no advantageous solution for adjusting the amplitude of the stroke when the suction is carried out by positive drive of the mobile assembly by the eccentric.

For some markets, such as waste water treatment, hydraulically actuated pumps are still seen as a complicated product requiring costly monitoring and maintenance. In addition, users still fear a rupture of the membrane which can lead to mixing of the treated liquid with the control fluid (oil) with significant consequences in terms of pollution. The remedy for this risk exists by the installation of double membranes with rupture detection device, which effectively complicates the devices in the eyes of users accustomed to simpler equipment.

The present invention is a response adapted to the state of the market, that is to say a mechanism for adjusting the flow rate of a pump with mechanical actuation having the same advantages as a pump with hydraulic control with regard to the ease of adjustment and conservation of pumping characteristics whatever the flow rate.

To this end, it therefore relates to a movable equipment for driving an alternative pump, with adjustable stroke comprising a slide mounted sliding in a fixed guide, cooperating by one of its ends with an eccentric motor device, whose eccentricity defines the maximum amplitude of the stroke of the slide in the guide, and coupled by its other end to the active pumping member which can be either a membrane, or by extension a rigid piston. In what follows we will only refer to diaphragm pumps, but the invention applies to all alternative pumps regardless of the nature of the piston coupled to the moving element.

According to the invention the slide is telescopic with two sliding parts, one relative to the other, parallel to the guide, one drive being coupled to the eccentric, and the other driven being coupled to the membrane, the two parts being, in the retracted state of the slide, held in abutment against each other by means of a coupling member developing a determined holding force while the driven piece of the slide has a cooperating stop member with an adjustable stop along the guide, hampering the travel of this driven part to limit the amplitude to a fraction of the maximum amplitude generated by the rotation of the eccentric, and opposing the holding effort an appropriate effort , leading to the extension of the slide.

In a first embodiment, the coupling member comprises at least one movable element for locking the two parts which cooperates with a cam surface carried by one of the parts tending to obliterate the movable element radially in a housing provided in the other part, against an elastic return member which defines the predetermined effort to overcome to make possible the extension of the slide. This embodiment has two advantages: the first lies in the fact that the predetermined force to be overcome defines the suction height of the pump which remains constant regardless of the adjustment of the stroke. The second results from the erasure of the locking member which no longer exerts any significant residual force between the driving part and the driven part of the slide, so that the stop of the driven part is not subjected more constraint.

Preferably, the end of the driving part of the slide opposite the eccentric has a bore in which is slidably mounted the end of the driven part opposite the membrane, the movable locking element being constituted by a ball housed in a recess formed radially in one of the parts subjected to the effect of an elastic member tending to extract it from the recess, the cam surface being constituted by the side of a groove formed in the other part . If the recess is provided in the driven part and the groove in the driving part, in a first variant the elastic element is arranged in the radial recess, and in a second variant the elastic element consists of a spring housed axially in the driven part, interposed between a fixed support of the latter and a cam, sliding axially in the driven part, which bears under the effect of the spring on the ball by a diverging cam surface. In the latter case, the cam or the driven part comprises a member for adjusting the spring setting.

If the recess is provided in the driving part and the groove in the driven part, the elastic member may be an elastic strip disposed in an external groove of the driving part into which the recess opens.

In another form of this first embodiment, the coupling member comprises a claw integral with one of the parts, having a plurality of teeth elastically deformable in a radial direction and whose free ends, which form the element movable locking, are engaged in a groove of the other part, in the retracted state of the slide.

In a second embodiment, the coupling member comprises a locking pawl pivoting on the driven part and engaged behind a stop of the driving part when the slide is retracted, under the effect of an elastic member, this pawl being integral with an operating lever whose free end constitutes the stop member of the driven part pivoting against the effect of the elastic member in the direction of release of the pawl when in contact with the adjustable stop along the guide.

Finally, in a third embodiment, the coupling member is constituted by a calibrated elastic member disposed between the two parts of the slide and the effect of which tends to keep the slide in its retracted position under a determined force.

The elastic member may consist of an elastomer part, in each of the embodiments except perhaps the case of the external elastic strip presented above.

• les figures 1, 2 et 3 sont trois schémas illustrant les moyens généraux de l'invention vus en coupe le long du plan axial de symétrie d'une pompe à membrane, dans trois états particuliers de la course de l'équipage mobile,
• les figures 4A et 4B représentent, vu en coupe, un premier mode de réalisation de l'invention dans deux états différents de l'équipage mobile,
• la figure 4C illustre une variante d'un détail de ce premier mode de réalisation,
• les figures 5A et 5B illustrent par des vues semblables, une variante de réalisation des figures 4A et 4B,
• les figures 6A et 6B illustrent une autre variante de la réalisation de l'équipage mobile de l'invention,
• les figures 7A et 7B sont des vues semblables aux précédentes d'une autre variante de réalisation,
• les figures 8A et 8B représentent un second mode de réalisation de l'équipage mobile selon l'invention,
• les figures 9A et 9B sont des vues d'un troisième mode de réalisation.
• la figure 10 est un schéma d'une variante de détail.

Other features and advantages of the invention will emerge from the description below of various embodiments made with reference to the appended drawings in which:

• FIGS. 1, 2 and 3 are three diagrams illustrating the general means of the invention seen in section along the axial plane of symmetry of a diaphragm pump, in three particular states of the stroke of the moving assembly,
• FIGS. 4A and 4B represent, seen in section, a first embodiment of the invention in two different states of the moving assembly,
• FIG. 4C illustrates a variant of a detail of this first embodiment,
• FIGS. 5A and 5B illustrate by similar views, an alternative embodiment of FIGS. 4A and 4B,
• FIGS. 6A and 6B illustrate another variant of the embodiment of the mobile assembly of the invention,
• FIGS. 7A and 7B are views similar to the previous ones of another alternative embodiment,
• FIGS. 8A and 8B represent a second embodiment of the mobile assembly according to the invention,
• Figures 9A and 9B are views of a third embodiment.
• Figure 10 is a diagram of a variant detail.

A diaphragm pump is shown diagrammatically in FIG. 1 and comprises a pumping head 1 in which a diaphragm 2 defines a pumping chamber 3 which is connected to a suction pipe 4 and a delivery pipe 5 through one-way valves 6 and 7.

The diaphragm 2 of this pump is coupled to one of the ends of a slide 8, the other end of which cooperates with an eccentric 9 for driving by means of a sliding pad 10 acting sometimes on the face 11 of the slide, sometimes on its face 12 to transform the continuous rotary movement A of the eccentric 9 into an alternative rectilinear movement B of the slide.

The slide 8 is guided in its front part by a fixed guide 13 belonging to the pump frame and is supported at its rear part by the axis 10 a of rotation of the eccentric by means of the edges of the light 14 traversed by this axis. The section of the slide in the guide is circular, or of any shape suitable for simple machining of the guide and the slide.

The slide 8 is made in two parts 15 and 16 so as to be telescopic. Thus the part 15 which is coupled to the membrane 2 has one end 17 slidingly mounted, parallel to the guide 13, in a bore 18 of the part 16 cooperating with the eccentric 9,10. In the retracted position of the slide, the front end 18 a of the part 16 rests on a shoulder 17 a of the part 15, the part 17 then being completely housed in the bore 18.

The two parts 15 and 16 are linked by a coupling device whose function will be explained with reference to its schematic representation 19 of FIGS. 1 to 3.

This device comprises two balls 20 and 21 housed in a diametrical recess 22 of the part 17 of the part 15. These two balls are urged by an elastic member 23 tending to push them out of the recess. The bore 18 has a groove 24 arranged so that, when the slide is retracted, the balls 20 and 21, under the effect of the elastic member 23, penetrate at least partially into the groove 24 s' pressing on the blank 25 of this groove which is turned away from the front face 18 a of the part 16. This flank 25 plays the role of a cam surface (it can for this purpose be inclined) which receives the effort developed by the resilient member 23 and transmitted by the balls and which transmits to the part 16 an axial component tending to keep the support piece on the shoulder 17a of the piece 15.

The intensity of this effort depends on the effort generated by the elastic member 23 and on the geometry of the ball contact surfaces 20, 21 / side 25 of the groove 24. It is therefore understood that as long as the effort tends to separate the two parts 15 and 16 is less than this coupling force, the slide behaves as if it were a single piece. On the other hand, if this force is greater than the coupling force, the balls 20 and 21 are erased by the cam side 25 of the groove 24 and the two parts 15 and 16 slide relative to each other . It will be noted that the only force opposing this sliding is practically independent of the force developed by the spring 23 since it comes down to the sole friction forces of the balls on the wall of the bore 18.

The part 15, called the driven part, has a stop member 26, shown here in the form of a radial finger, which passes through the fixed guide 13 through a slot 27 whose length measured axially, is at least equal to the maximum amplitude of the stroke of the slide 8, that is to say 2 e if e is the eccentricity of the cam 9 relative to the rotation shaft 10 a . Opposite this finger 26, the fixed guide carries a stop 28 adjustable in position relative to the light, in the sliding direction. This stop 28 is here produced in the form of an eccentric disc by relative to a pivot axis 29 and angularly indexable about this axis by means not described and known in themselves, which may include a manual adjustment button. Thus, according to this indexing, the stop 28 more or less covers the light 27 and more or less limits the amplitude of the movement of the finger 26 in this light.

This adjustable stop constitutes the pump flow adjustment member, all other things being equal.

It will first be assumed that the stop 28 is in a position revealing a length of light 27 sufficient for the finger 26 to be able to travel a length of it 2 e . The rotation of the eccentric cam 9 generates an alternating movement of the slide 8. Its forward movement (the left of FIG. 1) constitutes the pump delivery phase. Its backward travel (the right in Figure 1) is the suction phase of the pump. During the discharge, the driving force developed by the cam is transmitted to the membrane by the slide 8 the two parts 16 and 15 resting one upon the other by their surfaces 18a, 17a. During suction, the engine force is transmitted to the membrane through the coupling mechanism 19, that is to say by the latch of the part 15 on the part 16 by means of the balls.

The suction force corresponds to the suction column which one wishes to be able to raise with the pump and this can easily be supported by the coupling device 19 (appropriate choice of the spring 23 and its calibration for determined ball dimensions). For an adjustment of the pump to its maximum flow capacity, the moving assembly therefore behaves like a rigid connecting rod assembly.

To obtain a fraction of the maximum flow rate, action is taken on the disc 28 which, overflowing into the lumen 27, will hinder the travel of the finger 26. When the latter comes into contact with the disc 28, the part 15 is blocked in its travel and resistant effort that it undergoes overcomes the effort of locking. The balls 20 and 21 then disappear in the recess 22 and the part 16 disengaged from the part 15 is only driven by the eccentric. This state is shown in Figure 2. The amount of product sucked into the chamber 3 is therefore limited to a fraction of the total amount that this chamber can accept due to the premature cessation of the backward movement of the membrane 2 .

FIG. 3 illustrates the return of the part 16 in the direction of the part 15 which it approaches by its surface 18 a on the surface 17 a of the shoulder, since it pushes in the direction of the neutral point before the pump to drive back the quantity of product previously aspirated. At the same time, the groove 24 allows the balls 20 and 21 to return to their original place and the two parts 15 and 16 are again coupled.

The suction-discharge cycle is thus repeated at each turn of the eccentric. It will be noted that as soon as the two parts are disengaged, the force for retaining the part 15 by the stop 28 is practically zero. Similarly, the resistive torque opposite the rotation of the eccentric while the parts 15 and 16 are disengaged is also almost zero. This results in an expenditure of energy and less wear on the moving parts. In addition, as the coupling force is constant, the suction power of the pump which directly depends on it remains constant regardless of the flow rate setting operated. The overall performance of the pump is therefore improved and remains good whatever the flow rate adopted.

FIGS. 4A and 4B are sectional views of a first practical embodiment of the invention, in the state of the mobile assembly respectively in FIGS. 1 and 2. These figures show some of the elements already described with the same references. The part 15 is here tubular with an internal shoulder 30, to receive a rod 31 having an end 32 in the manner of a valve which forms a cam surface cooperating with the balls 20 and 21. A spring 33 is interposed between the shoulder 30 and nut 34 integral with the rod 31. Its effect tends to apply the part 32 against the balls 20 and 21 in order to extract them radially from their housing 22. The nut 34 makes it possible to adjust the calibration of the spring 33, therefore the coupling force parts 15 and 16 and therefore the suction power of the pump. It will be noted in this regard that this disengageable coupling constitutes a protection security for the pump mechanism. In fact, if the suction pipe 4 becomes blocked, the resistant force can increase until overcoming the coupling force which will yield. This will have avoided subjecting the membrane to too great a stress which could lead to its premature rupture. Certain shaped membranes are in fact more resistant to the discharge force than to the suction force.

In Figure 4C we find the elements described in Figures 4A and 4B with the same references. The spring 33 is here interposed between the part 16 and the end 32 of the rod 31 sliding in the part 16. The advantage of this inverted assembly lies in the reduction of the force transmitted by the spring to the balls when the latter are retracted into their housing, because the hitch having been disengaged the spring relaxes during the continuation of the travel of the part 16.

FIGS. 5A and 5B each represent a variant of the preceding figures in the same states of the moving assembly. Also in these embodiments, the part 15 is tubular, the bore being blind on the side of the balls 20 and 21. It will be mentioned that the balls may be of a number greater than 2 and preferably three in number, housed in bores radials of the part 15 offset by 120 ° from each other. The bore 35 of the part 15 receives a sliding plunger which can have either the shape of a needle 36 or that of a ball 37 (each of these elements being half shown in the figures). A spring 38 is compressed behind this needle 36 or this ball 37, to apply them against the balls 20, 21 in order to force towards the outside of the part 15. A threaded plug 39 in the bore 35 serves to adjust the calibration of the spring 38. Another embodiment of this variant is illustrated in FIG. 10 where the spring 38 is constituted by a elastomer block 40 compressed behind the ball 37 by the threaded plug 39.

In FIGS. 6A and 6B, apart from certain elements already described with the same references, there is shown a reverse arrangement of the preceding ones as regards the place of the balls. These 41 are placed in the housings 42 of the part 16 and are forced to project towards the inside of the bore 18 by external elastic strips 43 housed in a groove 44 outside of the part 16 so as to be able to deform without being hindered by the guide 13. The part 17 of the part 15 has for its part a groove 45 for partially accommodating the balls 41 and resting on them by its side 46 facing the shoulder 17 a . The elastically deformable strip or strips 43 generate the coupling force of the two parts 15 and 16 for the same reasons as those given above. FIG. 6B is an image of the elastic deformation of these strips when the balls 41 are forced into their housing 42 after the coupling of the parts 15 and 16 has been disengaged.

The coupling device shown in FIGS. 7A and 7B is a kind of elastic clamp having a plurality of elastically deformable teeth 47 (produced for example by slitting a cylindrical sleeve) integral with the part 15. The ends 47 a of these teeth are engaged in the groove 24 of the part 16, one of the flanks 25 of which forms a cam surface for lifting the end 47 a of these teeth when the connection is disengaged. The teeth can be replaced by a cylindrical sleeve with an external bead capable of elastically constricting.

Another embodiment of the invention is shown in Figures 8A and 8B. The disengageable connection of the two parts is ensured here by a pawl 50 pivoting about an axis 51 carried by the part 15. The latter, unlike the previous embodiments, no longer has a sliding part in the bore 18 of the part 16. the front surface 18a of this member 16 bears on the end 15 is drawn to the part 15 and the pawl 50 is pivoted in a slot 52 of the workpiece 15. When the surfaces 18 a and 15 a are in contact, the end 53 of the pawl can engage in the groove 24 behind its side 25 of the part 16. This engagement is forced by an elastic member 54 which exerts its force on a lever 55 integral with the pawl and pivoting with it around the axis 51. The end 56 of this lever crosses the guide 13 through the light 27 to cooperate with the stop, the lever 55 rocks around the axis 51 and lifts the end 53 which comes out of the groove 24 and releases the connection of the parts 15 and 16.

When the link is disengaged, the force of the spring 54 on the lever and pawl assembly is countered by the two supports of the end 53 on the surface of the bore 18 and of the end 56 on the stop 28. Note finally that the connection of the two parts is restored when, on the one hand the faces 15 a and 18 a are in contact and, on the other hand, when the piece 15 has already been moved so that the lever can switch on again the effect of spring 54.

Finally, in FIGS. 9A and 9B, a last embodiment of the invention is shown. The part 17 of the part 15 is of smaller diameter than that of the bore 18 of the part 16. The annular space thus existing makes it possible to accommodate a spring 57 compressed between a shoulder 58 carried by the end of the part 17 and a shoulder 59 provided at the inlet of the bore 18. the force generated by the spring plate surfaces 17a and 18a against each other and constitutes the coupling effort. When this effort is overcome, parts 15 and 16 can move relative to each other (Figure 9B). This solution is only applicable for pumps with low suction head so that the coupling force remains low. In fact, unlike the other embodiments, in this case, for a given coupling force, the more the flow rate is adjusted to a low value, the more the spring is stressed beyond its setting value and the resistance force increases as and as the spring is compressed during the relative movement of the two parts, this resistant force being transmitted to the stop 28 via the finger 26 of the part 15. This is why it is preferable to use this solution for pumps with a low spring setting value and a relatively small variation in flow settings.

Claims (15)

1. Moving equipment for appyling reciprocating drive to the diaphragm (2) of a mechanically actuated diaphragm pump of adjustable stroke, the moving equipment comprising a slider (8) slidably mounted in a fixed guide (13) co-operating at one of its ends with an eccentric drive device (9-10) whose eccentricity (e) defines the maximum amplitude (2e) of the stroke of the slider (8) in the guide (13), and coupled at its other end to the membrane (2), the equipment being characterized in that the slider (8) is telescopic, having two pieces (15, 16) slidable relative to each other parallel to the guide (13), one of the pieces being a driving piece (16) which is coupled to the eccentric (9) and the other of the pieces being a driven piece (15) which is coupled to the diaphragm (2), both pieces being held pressed against each other when the slider (8) is in a retracted state by means of a coupling member (19) developing a determined holding force, while the driven piece (15) of the slider (8) possesses an abutment member (26) which co-operates with an abutment (28) whose position along the guide (13) is adjustable to interfere with the stroke of said driven piece (15) to limit its amplitude to a fraction of the maximum amplitude (2e) generated by rotation of the eccentric (9) and which opposes the holding force with a suitable force, thereby causing the slider (8) to be extended.
2. Moving equipment according to claim 1, characterized in that the coupling member (19) includes at least one moving locking item (20, 21) for locking together the two pieces (15, 16) and co-operating with a camming surface (25) carried by one of the two pieces (16) and tending to retract the moving item (20, 21) radially into a recess (22) provided in the other piece (15) against the force of a resilient return member (23).
3. Moving equipment according to claim 1 or 2, characterized in that the end of the driving piece (16) of the slider (8) furthest from the eccentric (9) includes a bore (18) in which the end (17) of the driven piece (15) furthest from the diaphragm (2) is slidably received, the moving locking item being constituted by a ball (20, 21) received in a recess (22) provided radially in one of the pieces and subjected to the effect of a resilient member (23) tending to urge it out from the recess, the camming surface being constituted by the side (25) of a groove (24) provided in the other piece (16).
4. Moving equipment according to claim 3, characterized in that the recess (22) is provided in the driven piece (15) and the groove (24) is provided in the driving piece (16).
5. Moving equipment according to claim 4, characterized in that the resilient member (23) is disposed in the radial recess (22).
6. Moving equipment according to claim 4, characterized in that the resilient member (33, 38) is constituted by a spring received axially in the driven piece (15) between a fixed abutment (30, 39) thereof and a cam (32, 36, 37) sliding axially in the driven piece (15) and bearing under thrust from the spring against the ball (20, 21) via a diverging camming surface.
7. Moving equipment according to claim 6, characterized in that the cam (31) or the driven piece (15) includes an adjustment member (34, 39) for setting the spring.
8. Moving equipment according to claim 6 or 7, characterized in that it includes a plurality of locking balls (20, 21) regularly distributed in a common radial plane in the driven piece (15).
9. Moving equipment according to claim 3, characterized in that the recess (42) is provided in the driving piece (16) and the groove (45) is provided in the driven piece.
10. Moving equipment according to claim 9, characterized in that the resilient member is constituted by at least one resilient blade (43) disposed in an external groove (44) of the driving pieces (16) into which the recess opens out.
11. Moving equipment according to claim 2, characterized in that the coupling member includes a claw (47) fixed to one of the pieces (15) and having a plurality of teeth (47) which are resiliently deformable in a radial direction and which have free ends, thereby forming the moving locking item, which teeth are engaged in a groove (24) of the other piece (16) when the slider (8) is in the retracted state.
12. Moving equipment according to claim 1, characterized in that the coupling member comprises a locking crank (50) rocking on the driven piece (15) and engaged behind an abutment (25) of the driving piece when the slider is retracted under urging from a resilient member (54), the crank including an operating lever (55) whose free end (56) constitutes the abutment member (26) of the driven piece (15) rocking against the effect of the resilient member (54) in the crank disengagement direction when coming into contact with the abutment (28) whose position along the guide is adjustable.
13. Moving equipment according to claim 1, characterized in that the coupling member is constituted by a rated resilient member (57) disposed between the two pieces (15, 16) of the slider and whose effect tends to hold the slider in its retracted position under a determined force.
14. Moving equipment according to any preceding claim, characterized in that the resilient member is constituted by a piece of elastomer (40).
15. Moving equipment according to any one of claims 1 to 11 and 13, characterized in that the abutment of the driven piece (15) is a radial finger (26) received in a longitudinal slot (27) of the fixed guide (13), the abutment (28) whose position along the guide can be adjusted being constituted by an eccentric disk (28) whose angular position about a pivot shaft (29) engaging the guide (13) and parallel to the finger (26) is adjustable so that the disk covers a length of the slot (27) which depends on its angular position.

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